CN110174074B - Measuring device and method for thermal deformation error compensation of industrial robot - Google Patents
Measuring device and method for thermal deformation error compensation of industrial robot Download PDFInfo
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Abstract
The invention discloses a measuring device for thermal deformation error compensation of an industrial robot and a robot thermal deformation error calibration method based on the measuring device. The measuring device comprises a robot tail end detection ball device and a robot tail end positioning detection device, wherein the robot tail end detection ball device consists of a connecting piece and a detection ball and is arranged at the tail end of the industrial robot; the robot tail end positioning detection device comprises a mounting bracket, a sensor mounting chassis and more than four laser ranging sensors, all the laser ranging sensors are surrounded into a circle and uniformly distributed on the sensor mounting chassis, the inclination angles are 45 degrees, and each laser ranging sensor is respectively connected with a robot controller for data communication. The measuring device and the measuring method can realize accurate identification of kinematic parameter errors of the industrial robot, improve the terminal positioning precision of the industrial robot, reduce the shutdown maintenance time of the industrial robot and further improve the automation degree of a production line.
Description
Technical Field
The invention relates to the technical field of industrial robot calibration, in particular to a measuring device and a measuring method for thermal deformation error compensation of an industrial robot.
Background
With the development of robot technology, industrial robots are increasingly used in the fields of welding, cutting, assembly and the like. By installing different end tools, the industrial robot is able to perform a variety of work tasks. However, as the industrial robot continuously operates, the positioning accuracy of the industrial robot is reduced due to environmental temperature change, heat dissipation of a servo motor, joint friction and the like, and the current task requirements cannot be met, and the main reason is that the temperature causes thermal deformation of a connecting rod and a joint, so that the change of the geometric parameters of the robot is caused, which is also a main factor affecting the accuracy of the industrial robot.
The current methods for thermal deformation error compensation of industrial robots are mainly divided into two types: (1) Based on the experimental test data in the earlier stage, a thermal deformation error correction model of the industrial robot is established by utilizing technologies such as an artificial neural network and the like, and thermal deformation error compensation is realized according to the model; (2) And the robot parameter calibration is completed periodically by using manpower, and the geometric parameters of the industrial robot are revised again, so that the operation precision of the industrial robot is improved. However, the first type of method is greatly affected by the modeling accuracy of the early correction model, and other unknown influencing factors cannot be fully considered. The second type of method periodically calibrates offline and consumes a great deal of human resources, thereby greatly reducing the productivity of the production line. At present, a plurality of periodic calibration methods for geometric parameters of a robot based on vision exist, but the method is greatly influenced by ambient light. Therefore, it is needed to provide a device and a method for rapidly and online detecting and compensating thermal deformation errors of an industrial robot, which can ensure the error compensation precision of the industrial robot and improve the automation degree of the industrial robot production line.
Disclosure of Invention
The invention aims to solve the technical problems of overcoming the technical defects and shortcomings in the prior art and providing a measuring device for thermal deformation error compensation of an industrial robot and a calibration method based on the measuring device.
In order to achieve the technical purpose, the technical scheme provided by the invention is as follows:
the measuring device for thermal deformation error compensation of the industrial robot is characterized by comprising a robot tail end detection ball device and a robot tail end positioning detection device;
the robot tail end detection ball device consists of a connecting piece and a detection ball, wherein the connecting piece comprises a flange plate and a connecting rod, one end of the connecting rod is fixedly connected with the detection ball, the other end of the connecting rod is fixedly connected with the flange plate, and the connecting piece is fixedly connected with the tail end flange plate of the industrial robot through the flange plate;
the robot tail end positioning detection device comprises a mounting bracket, a sensor mounting chassis and laser ranging sensor groups formed by more than four laser ranging sensors, wherein the laser ranging sensor groups are mounted on the sensor mounting chassis, the laser ranging sensors in the groups are surrounded on the sensor mounting chassis to form a circle and are uniformly distributed and are positioned on the same measuring plane, and the laser emission directions face the inner side of the sensor mounting chassis and form an included angle of 45 degrees with the measuring plane; the measuring plane is parallel to the XOY plane of the industrial robot base coordinate system, and each laser ranging sensor is respectively connected with the robot controller for data communication; the sensor installation chassis is fixedly installed at the top of the installation support.
In addition to the above, a further improved or preferred embodiment further includes:
the sensor installation chassis is provided with a circular tray body, the periphery of the tray body is provided with an upward protruding outer edge, the outer edge is provided with a plurality of evenly distributed fixing grooves, the number of the fixing grooves is not less than that of the laser ranging sensors, and the fixing grooves are formed by oblique cuts formed in the outer edge and are used for installing the laser ranging sensors.
The upper surface of disk body is parallel with the measuring plane of robot terminal location detection device, the bottom surface of inclined cut and the contained angle of disk body upper surface are 45.
The processing precision of the detection ball is required to meet the requirement that the error of the distance from any point on the spherical surface to the center of the sphere is not more than 0.01mm.
Preferably, the number of the laser ranging sensors is designed to be 6, and the laser ranging sensors are uniformly distributed on the sensor mounting chassis at a circle center included angle of 60 degrees.
The robot thermal deformation error calibration method based on the measuring device is characterized by comprising the following steps of:
step 1: the method comprises the steps of installing a robot tail end detection ball device at the tail end of an industrial robot subjected to precision calibration, arranging a robot tail end positioning detection device at one side of the industrial robot, and fixedly installing the industrial robot on a production line;
moving the robot tail end detection ball device into the detection range of the robot tail end positioning detection device by a manual teaching method, enabling each laser ranging sensor in the laser ranging sensor group to measure the detection ball, and obtaining a basic coordinate system phi of the industrial robot B Measurement coordinate system phi with robot tail end positioning detection device M Conversion matrix between M R B And detecting a conversion matrix R from the spherical center coordinates to the end flange coordinates of the industrial robot T And the position of the end flange plate under the industrial robot base coordinate system at the moment is recorded as the nominal position P of the default tool coordinate point Nj ；
Step 2: after a period of operation, controlling the industrial robot to enter a detection range of a robot tail end positioning detection device according to the pose taught manually, judging whether the positioning precision of the industrial robot can meet the production requirement, and if not, entering the following steps;
the method comprises the following steps: changing the tail end pose of the industrial robot, and controlling the industrial robot to enable a tail end detection ball device of the robot to be in the detection range of the tail end positioning detection device, namely, each laser ranging sensor can detect the detection ball;
step 4: the measurement data of each laser ranging sensor is respectively recorded as L i (i=1, 2, …, n; n is greater than or equal to 4), establishing a local coordinate system phi of each laser ranging sensor i (i=1, 2, …, n; n is greater than or equal to 4), the local coordinate system phi is obtained according to the structural parameters of the sensor installation chassis i Measurement coordinate system phi with robot tail end positioning detection device M Is a conversion matrix of (a) M R i ；
Step 5: measuring points of the detection ball surface corresponding to the laser ranging sensors in a corresponding local coordinate system phi i The lower seat mark is(i=1, 2, …, n; n is larger than or equal to 4), and converting the coordinates of the measuring point into a measuring coordinate system phi of the robot tail end positioning detection device according to the coordinate system conversion relation M Hereinafter, it is denoted as P Mi ＝(x i ，y i ，z i )(i＝1,2,…,n；n≥4)；
Step 6: let P be r ＝(x r ,y r ,z r ) Measurement coordinate system phi of positioning detection device at tail end of robot for detecting sphere center M Lower coordinates, using P Mi ＝(x i ，y i ，z i ) (i=1, 2, …, n; n is larger than or equal to 4), n sphere center distance formulas (x) can be obtained i -x r ) 2 +(y i -y r ) 2 +(z i -z r ) 2 ＝r 2 (i＝1,2,…,n；n≥4)；
Step 7: the n sphere center distance formulas in the step 6 only have three unknown parameters, an overdetermined equation set is formed, and the measurement coordinate system phi of the sphere center of the detection sphere (302) at the tail end of the robot positioning detection device can be calculated by using a least square method M Lower coordinate P r ；
According to the two conversion matrices in step 1 M R B And R is T By P r Calculating to obtain the coordinate of the end flange plate under the industrial robot base coordinate system, and marking the coordinate as the position P of the default tool coordinate point j The nominal position of the default tool coordinate point under the base coordinate system of the industrial robot is known as P Nj The positioning error delta P=P of the industrial robot can be obtained j -P Nj Recording delta P and the space coordinates of each joint of the industrial robot;
step 8: repeatedly executing the steps 3 to 7, so that the execution times of the steps 3 to 7 are not less than 30 times;
step 9: and (3) taking all delta P and the corresponding joint space coordinates into a position error model of the industrial robot, calculating the kinematic parameters of the industrial robot after calibration by using a least square method, and updating the kinematic parameters into a control module of a robot controller to realize the compensation of the thermal deformation error of the industrial robot.
Further, in step 9, the industrial robot position error model is established based on the parameter method of the MDH model, and the position error model formula is as follows:
D＝J θ Δθ+J a Δa+J α Δα+J d Δd+J β Δβ
in the above formula:
d represents the positioning error of the industrial robot tip, Δp;
Δθ＝[Δθ 1 Δθ 2 … Δθ m ]
Δα＝[Δα 1 Δα 2 … Δα m ]
Δa＝[Δa 1 Δa 2 … Δa m ]
Δd＝[Δd 1 Δa 2 … Δa m ]
Δβ＝[Δβ 1 Δβ 2 … Δβ m ]
in the MDH model, the coordinate system relation between two adjacent joints of the industrial robot is described by four parameters, namely joint rotation angles theta k Angle alpha of torsion of connecting rod k Length of connecting rod a k And joint distance d k Parameter beta k Is the axis Z of two adjacent joints k-1 And Z k In parallel to axis X k And Z k Included angle on the plane of (2);
k is the label of the joint, k=1, 2 … m, m is a positive integer;
each Δθ in brackets k 、Δα k 、Δa k 、Δd k 、Δβ k The geometric parameter errors of the five parameters are respectively;
delta theta, delta alpha, delta a, delta d and delta beta are respectively the set of the geometric parameter errors of the above parameters of each joint;
J θ J a 、J α 、J d 、J β is a corresponding Jacobian matrix;
preferably, the number of times of execution of steps 2 to 6 is generally set to 50.
In the working process of the industrial robot, the step 2 is periodically executed, namely, error calibration is carried out on the industrial robot once at intervals so as to maintain the working precision of the industrial robot.
The beneficial effects are that:
1) Compared with a visual measurement system, the measuring device for thermal deformation error compensation of the industrial robot is not influenced by ambient light, and has good measuring precision, stability and low price; compared with measuring equipment such as a laser tracker and the like, the cost of the system can be reduced; the dependency on the movement of the robot is reduced compared to the calibration device of patent 201610351194.9, both devices having the same price, but the measuring accuracy of the measuring device of the present application is relatively high.
2) According to the robot thermal deformation error calibration method based on the measuring device, the end error of the industrial robot is detected with high precision through the laser ranging sensor, and the error calibration program is optimally designed, so that the accurate identification of the kinematic parameter error of the industrial robot is realized, the end positioning precision of the industrial robot is improved, the shutdown maintenance time of the industrial robot can be further reduced, and the automation degree of a production line is improved.
Drawings
FIG. 1 is a schematic diagram of the installation of a thermal deformation error compensated measurement device of the present invention;
FIG. 2 is a schematic view of a robotic end-of-range ball apparatus of the present invention;
FIG. 3 is a block diagram of a robot end position detection device according to the present invention;
FIG. 4 is a block diagram of a sensor mounting chassis of the present invention;
FIG. 5 is a schematic view of a sensor mounting bracket of the present invention;
FIG. 6 is a schematic diagram of a robotic end position detection of the present invention;
fig. 7 is a schematic diagram of a robotic end position calculation of the present invention.
Detailed Description
In order to further clarify the principles of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
Embodiment one:
the measuring device for thermal deformation error compensation of the industrial robot as shown in fig. 1 to 6 comprises a robot end detection ball device 3, a robot end positioning detection device 4 and other components. In this embodiment, the robot end positioning detection device 4 and the industrial robot 2 are both disposed on a horizontal plane, so that the measurement plane of the robot end positioning detection device 4 is parallel to the XOY plane of the industrial robot 2 base coordinate system
The robot tail end detection ball device 3 is composed of a connecting piece 301 and a detection ball 302, wherein the connecting piece 301 comprises a flange plate and a connecting rod, one end of the connecting rod is fixedly connected with the detection ball 302, the other end of the connecting rod is fixedly connected with the flange plate, and the connecting piece 301 is fixedly connected with the tail end flange plate of the industrial robot through the flange plate. The machining precision of the spherical surface of the detection ball 302 is better than 0.01mm, namely the error of the distance from any point on the spherical surface to the center of the sphere is not more than 0.01mm.
The robot end positioning detection device 4 comprises a mounting bracket 401, a sensor mounting chassis 402 and six laser ranging sensors 403, 404, 405, 406, 407, 408 (fewer than four laser ranging sensors may have errors). The sensor mounting chassis 402 is equipped with circular shape disk body, and disk body week side is equipped with the outer edge that makes progress the arch, outer edge is equipped with six fixed slots of evenly distributed, the fixed slot comprises the oblique incision of seting up on outer edge for install laser range sensor. The six laser ranging sensors are surrounded into a circle and uniformly distributed on the sensor mounting chassis 402, the inclined angles are all 45 degrees (the included angle between the bottom surface of the inclined notch and the plane of the base plate is 45 degrees), and the six laser ranging sensors are respectively connected with the robot controller 1 through an RS-485 bus for data communication. And the sensor mounting chassis 402 is secured to the top of the mounting bracket 401 by four mounting holes located in the center of its body that cooperate with locking means.
The working principle of performing thermal deformation error compensation on the industrial robot by using the measuring device is that firstly, the industrial robot 2 after being subjected to precision calibration (i.e. thermal deformation is not generated yet, and the precision meets the operation requirement) moves a robot tail end detection ball device 3 installed at the tail end of the industrial robot 2 to the detection range of a robot tail end positioning detection device 4 by a manual teaching method, so that all six laser ranging sensors 403, 404, 405, 406, 407 and 408 can measure a detection ball 302, and the numerical values of the laser ranging sensors 403, 404, 405, 406, 407 and 408 are approximately equal; when the industrial robot 2 works continuously for a period of time, i.e. thermal deformation can be generated, the method can periodically enter the detection range of the robot tail end positioning detection device 4 according to the pose taught by the initial manual, judge whether the positioning precision of the industrial robot 2 can meet the production requirement, and enter the program step of error calibration if the positioning precision does not meet the production requirement.
Embodiment two:
taking a six-joint industrial robot as an example on the basis of the first embodiment, the error calibration of thermal deformation of the six-joint industrial robot is performed by using the measuring device of the first embodiment, and the specific process is as follows:
the robot thermal deformation error calibration method based on the measuring device comprises the following steps:
step 1: the method comprises the steps of installing a robot tail end detection ball device 3 at the tail end of an industrial robot 2 after accuracy calibration, arranging a robot tail end positioning detection device 4 at one side of the industrial robot 2, and fixedly installing the industrial robot 2 on a production line;
by means of manual teaching, the robot tail end detection ball device 3 is moved into the detection range of the robot tail end positioning detection device 4, so that each laser ranging sensor in the laser ranging sensor group can measure the detection ball 302, and a base coordinate system phi of the industrial robot 2 is obtained B Measurement coordinate system phi with robot end position detection device 4 M Conversion matrix between M R B And detecting a conversion matrix R from the spherical center coordinates of the ball 302 to the end flange coordinates of the industrial robot 2 T And the position of the end flange plate under the industrial robot base coordinate system at the moment is recorded as the nominal position P of the default tool coordinate point Nj ；
Step 2: after a period of operation, controlling the industrial robot 2 to enter a detection range of a robot tail end positioning detection device 4 according to the pose taught manually, judging whether the positioning precision of the industrial robot 2 can meet the production requirement, and if not, entering the following steps;
step 3: changing the tail end pose of the industrial robot, and controlling the industrial robot 2 to enable the tail end detection ball device 3 of the robot to be in the detection range of the tail end positioning detection device 4, namely, each laser ranging sensor can detect the detection ball 302;
step 4: the measurement data of each laser ranging sensor is respectively recorded as L i (i=1, 2, …, 6), establishing a local coordinate system Φ of each laser ranging sensor i (i=1, 2, …, 6), the local coordinate system Φ is obtained from the structural parameters of the sensor-mounting chassis 402 i Measurement coordinate system phi with robot end position detection device 4 M Is the conversion matrix of (a) M R i ；
Step 5: the laser distance measuring sensors are shot at the measuring points on the surface of the detecting ball 302 in a local coordinate system phi i The lower seat mark is(i=1, 2, …, 6) converting the coordinates of the measurement point to the measurement coordinate system Φ of the robot end position detecting device 4 according to the coordinate system conversion relation M Hereinafter, it is denoted as P Mi ＝(x i ，y i ，z i )(i＝1,2,…,6)；
Step 6: let P be r ＝(x r ,y r ,z r ) Measurement coordinate system phi of the robot end positioning detection device 4 for detecting the sphere center of the sphere 302 M Lower coordinates, using P Mi ＝(x i ，y i ，z i ) (i=1, 2, …, 6) 6 center-of-sphere distance formulas (x) can be obtained i -x r ) 2 +(y i -y r ) 2 +(z i -z r ) 2 ＝r 2 (i＝1,2,…,6)；
Step 7: the six sphere center distance formulas in the step 6 only have three unknown parameters, so as to form an overdetermined equation set, and the measurement coordinate system phi of the sphere center of the detection sphere 302 in the robot tail end positioning detection device 4 can be calculated by using a least square method M Lower coordinate P r ；
According to the two conversion matrices in step 1 M R B And R is T By P r Calculating to obtain the coordinate of the end flange plate under the industrial robot base coordinate system, and marking the coordinate as the position P of the default tool coordinate point j The nominal position of the default tool coordinate point under the 2-base coordinate system of the industrial robot is known as P Nj The positioning error Δp=p of the industrial robot 2 can be obtained j -P Nj Recording delta P and the space coordinates of each joint of the industrial robot 2;
step 8: repeating the steps 3 to 7, wherein the execution times are not less than 30 times, and 50 times are generally taken;
step 9: the position error model is established based on the MDH model parameter method as follows:
D＝J θ Δθ+J a Δa+J α Δα+J d Δd+J β Δβ
in the above formula:
d represents the positioning error of the industrial robot tip, Δp;
Δθ＝[Δθ 1 Δθ 2 … Δθ 6 ]
Δα＝[Δα 1 Δα 2 … Δα 6 ]
Δa＝[Δa 1 Δa 2 … Δa 6 ]
Δd＝[Δd 1 Δa 2 … Δa 6 ]
Δβ＝[Δβ 1 Δβ 2 … Δβ 6 ]
in the MDH model, the coordinate system relation between two adjacent joints of the industrial robot is described by four parameters, namely joint rotation angles theta k Angle alpha of torsion of connecting rod k Length of connecting rod a k And joint distance d k Parameter beta k Is the axis Z of two adjacent joints k-1 And Z k In parallel to axis X k And Z k K is the joint index, in this embodiment, k=1, 2 … 6.
Δθ in brackets k 、Δα k 、Δa k 、Δd k 、Δβ k Respectively the geometric parameter errors of the five parameters corresponding to the kth joint; Δθ, Δα, Δa, Δd, and Δβ are the sets of the above-mentioned parameter geometric parameter errors for each joint, respectively.
J θ J a 、J α 、J d 、J β Is a corresponding Jacobian matrix;
and (3) taking all delta P obtained in the step (7) and the corresponding space coordinates of each joint into a position error model of the industrial robot, calculating by using a least square method to obtain relatively accurate kinematic parameters of the industrial robot 2, and updating the kinematic parameters into a control module of the robot controller 1 to realize the compensation of the thermal deformation error of the industrial robot 2.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the foregoing embodiments, which have been described in the foregoing embodiments and description merely illustrates the principles of the invention, and various changes and modifications may be made therein without departing from the spirit and scope of the invention, the scope of which is defined in the appended claims, specification and their equivalents.
Claims (8)
1. The robot thermal deformation error calibration method is realized by a measuring device for industrial robot thermal deformation error compensation, and is characterized in that:
the measuring device for thermal deformation error compensation of the industrial robot comprises a robot tail end detection ball device (3) and a robot tail end positioning detection device (4);
the robot tail end detection ball device is composed of a connecting piece (301) and a detection ball (302), wherein the connecting piece (301) comprises a flange plate and a connecting rod, one end of the connecting rod is fixedly connected with the detection ball (302), the other end of the connecting rod is fixedly connected with the flange plate, and the connecting piece (301) is fixedly connected with the tail end flange plate of the industrial robot through the flange plate;
the robot tail end positioning detection device (4) comprises a mounting bracket (401), a sensor mounting chassis (402) and laser ranging sensor groups formed by more than four laser ranging sensors, wherein the laser ranging sensor groups are mounted on the sensor mounting chassis (402), the laser ranging sensors in the groups are surrounded on the sensor mounting chassis (402) to form a circle and are uniformly distributed and are positioned on the same measuring plane, and the laser emission directions face the inner side of the sensor mounting chassis (402) and form an included angle of 45 degrees with the measuring plane; the measuring plane is parallel to an XOY plane of the industrial robot base coordinate system, and each laser ranging sensor is respectively connected with the robot controller (1) for data communication; the sensor mounting chassis (402) is fixedly mounted on the top of the mounting bracket (401);
the method comprises the following steps:
step 1: the method comprises the steps of installing a robot tail end detection ball device (3) at the tail end of an industrial robot (2) subjected to precision calibration, arranging a robot tail end positioning detection device (4) at one side of the industrial robot (2), and fixedly installing the industrial robot (2) on a production line;
by teaching manuallyThe method comprises the steps of moving a robot tail end detection ball device (3) into the detection range of a robot tail end positioning detection device (4), enabling each laser ranging sensor in a laser ranging sensor group to measure the detection ball (302), and acquiring a base coordinate system phi of an industrial robot (2) B Measurement coordinate system phi with robot end positioning detection device (4) M Conversion matrix between M R B And detecting a conversion matrix R from the coordinates of the sphere center of the sphere (302) to the coordinates of the flange at the tail end of the industrial robot (2) T And the position of the end flange plate under the industrial robot base coordinate system at the moment is recorded as the nominal position P of the default tool coordinate point Nj ；
Step 2: after a period of operation, controlling the industrial robot (2) to enter a detection range of a robot tail end positioning detection device (4) according to the pose taught manually, judging whether the positioning precision of the industrial robot (2) can meet the production requirement, and if not, entering the following steps;
step 3: changing the tail end pose of the industrial robot, and controlling the industrial robot (2) to enable a tail end detection ball device (3) of the robot to enter a detection range of a tail end positioning detection device (4), namely, each laser ranging sensor can detect the detection ball (302);
step 4: the measurement data of each laser ranging sensor is respectively recorded as L i I=1, 2, …, n, n is larger than or equal to 4, and a local coordinate system phi of each laser ranging sensor is established i Obtaining the local coordinate system phi according to the structural parameters of the sensor mounting chassis (402) i Measurement coordinate system phi with robot end positioning detection device (4) M Is a conversion matrix of (a) M R i ；
Step 5: measuring points of the surface of the detection ball (302) corresponding to the laser ranging sensors in a corresponding local coordinate system phi i The lower seat mark isAccording to the coordinate system conversion relation, converting the coordinates of the measurement points to a measurement coordinate system phi of the robot tail end positioning detection device (4) M Hereinafter, recordIs P Mi ＝(x i ，y i ，z i )；
Step 6: let P be r ＝(x r ,y r ,z r ) Measuring coordinate system phi of the robot end positioning detection device (4) for detecting the sphere center of the sphere (302) M Lower coordinates, using P Mi ＝(x i ，y i ，z i ) N sphere center distance formulas (x) can be obtained i -x r ) 2 +(y i -y r ) 2 +(z i -z r ) 2 ＝r 2 ；
Step 7: the n sphere center distance formulas in the step delta only have three unknown parameters, an overdetermined equation set is formed, and the measurement coordinate system phi of the sphere center of the detection sphere (302) on the tail end positioning detection device (4) of the robot can be calculated by using a least square method M Lower coordinate P r ；
According to the two conversion matrices in step 1 M R B And R is T By P r Calculating to obtain the coordinate of the end flange plate under the industrial robot base coordinate system, and marking the coordinate as the position P of the default tool coordinate point j The nominal position of the default tool coordinate point under the base coordinate system of the industrial robot (2) is known as P Nj The positioning error delta P=P of the industrial robot (2) can be obtained j -P Nj Recording delta P and the space coordinates of each joint of the industrial robot (2);
step 8: repeatedly executing the steps 3 to 7, so that the execution times of the steps 3 to 7 are not less than 30 times;
step 9: and (3) taking all delta P and the corresponding joint space coordinates into a position error model of the industrial robot, calculating the kinematic parameters of the industrial robot (2) after calibration by using a least square method, and updating the kinematic parameters into a control module of a robot controller (1) to realize the compensation of the thermal deformation error of the industrial robot (2).
2. The method for calibrating the thermal deformation error of the robot according to claim 1, wherein the method comprises the following steps:
in step 9, the position error model of the industrial robot is established based on the parameter method of the MDH model, and the position error model formula is as follows:
D＝J θ Δθ+J a Δa+j α Δα+J d Δd+J β Δβ
in the above formula:
d represents the positioning error of the industrial robot tip, Δp;
Δθ＝[Δθ 1 Δθ 2 ... Δθ m ]
Δα＝[Δα 1 Δα 2 ... Δα m ]
Δα＝[Δα 1 Δα 2 ... Δα m ]
Δd＝[Δd 1 Δα 2 ... Δα m ]
Δβ＝[Δβ 1 Δβ 2 ... Δβ m ]
in the MDH model, the coordinate system relation between two adjacent joints of the industrial robot is described by four parameters, namely joint rotation angles theta k Angle alpha of torsion of connecting rod k Length of connecting rod alpha k And joint distance d k Parameter beta k Is the axis Z of two adjacent joints k-1 And Z k In parallel to axis X k And Z k Included angle on the plane of (2);
k is the label of the joint, k=1, 2 … m, m is a positive integer;
Δθ in brackets k 、Δα k 、Δa k 、Δd k 、Δβ k The geometric parameter errors of the five parameters are respectively;
delta theta, delta alpha, delta a, delta d and delta beta are respectively the set of the geometric parameter errors of the above parameters of each joint;
J θ 、J α 、J α 、J d 、J β is the corresponding jacobian matrix.
3. The method for calibrating thermal deformation errors of a robot according to claim 1 or 2, wherein the number of execution times of the steps 2 to 6 is 50.
4. The method for calibrating thermal deformation errors of a robot according to claim 1 or 2, wherein step 2 is periodically performed during operation of the industrial robot.
5. The method for calibrating the thermal deformation error of the robot according to claim 1, wherein the sensor mounting chassis (402) is provided with a circular tray body, the periphery of the tray body is provided with an upward protruding outer edge, the outer edge is provided with a plurality of uniformly distributed fixing grooves, the number of the fixing grooves is not less than that of the laser ranging sensors, and the fixing grooves are formed by oblique cuts formed in the outer edge and are used for mounting the laser ranging sensors.
6. The method for calibrating the thermal deformation error of the robot according to claim 5, wherein the upper surface of the tray body is parallel to the measuring plane of the robot tail end positioning and detecting device (4), and the included angle between the bottom surface of the oblique notch and the upper surface of the tray body is 45 degrees.
7. The method for calibrating the thermal deformation error of the robot according to claim 1, wherein the machining precision of the detection ball (302) is required to meet the condition that the distance error from any point on the spherical surface to the spherical center is not more than 0.01mm.
8. The method for calibrating the thermal deformation error of the robot according to claim 1, wherein the number of the laser ranging sensors is 6, and the laser ranging sensors are uniformly distributed on a sensor mounting chassis (402) at a circle center included angle of 60 degrees.
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| CN112276942B (en) * | 2020-09-30 | 2021-10-29 | 成都卡诺普机器人技术股份有限公司 | Consistency compensation method for robot arm |
| CN113103234B (en) * | 2021-04-15 | 2022-03-04 | 东南大学 | Many stay wire sensor position measurement system based on magnetism adsorbs |
| CN113752297B (en) * | 2021-09-07 | 2023-03-03 | 浙江理工大学 | Industrial robot self-calibration device and method based on circumference sealing principle |
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